Cylinder blocks of modern internal combustion engines are produced as a rule in a casting process. Since the material which is used for the cylinder block (as a rule, aluminum or iron, but magnesium/aluminum composite materials may also be suitable) is not capable of meeting the tribological requirements necessary for a friction-free and therefore as far as possible wear-free movement of piston in the cylinder, what are known as cylinder liners are used in the cylinders. They have the required tribological properties and, as a consequence, ensure largely wear-free long-term operation of piston in the cylinder block; cylinder liners of this type are frequently provided with a circumferential face which is roughened, grooved or machined in a similar way. As an alternative to this, the prior art also teaches the application of an aluminum spray coating to the circumferential face of the cylinder liner. In both cases, a particularly positively locking connection of the cylinder liner to the cylinder block can be produced during the casting encapsulation (likewise known from the prior art) of the cylinder liner with an aluminum alloy.
In an analogous way, the production of pistons for internal combustion engines of this type also as a rule takes place by means of a casting process. What are known as piston rings (as a rule made of steel) are used to seal the piston against the cylinder block, which piston rings can be inserted into a circumferential groove which is provided on a circumferential face of the piston, in order to produce said sealing effect. In order then to reduce the tribological loading of the piston, the piston material of which consists as a rule of a lightweight aluminum alloy, with respect to the piston ring which is formed from a steel, what are known as piston ring carriers are used in conventional pistons, which piston ring carriers are encapsulated by casting with the actual piston in one casting operation. As a consequence, there is no more direct piston/piston ring boundary surface which is critical for wear to a particular extent; rather, said piston ring carrier then acts as a mechanical “interface” between the piston ring and the actual piston, the circumferential groove for receiving the piston ring then being provided on the piston ring carrier.
U.S. Pat. No. 4,273,835 describes the production of a cylinder block with a cylinder liner which is inserted into the cylinder of the cylinder block. A silicone resin layer for sealing a water jacket is provided between the cylinder liner and the cylinder block.
JP 2010-156003 A describes the coating of a workpiece made of cast iron with an adapter layer which contains carbon, manganese, silicon, sulfur and phosphorus. The adapter layer increases the bond strength of an aluminum alloy which is applied to the workpiece.
A particularly positively locking connection between the cylinder liner and the cylinder block and between the piston ring carrier and the piston (in the following text, the two components are in each case called an “insert part” and “cast component” in generalized terms) arises, however, if what is known as an aluminum high pressure die casting process is used for casting encapsulation of the insert part with an aluminum alloy, which process is however increasingly dispensed with (often for cost reasons) during the production of modern internal combustion engines in favor of low pressure die casting techniques or gravity die casting techniques. By means of low pressure or gravity die casting techniques, the quality of the positively locking connection of the insert part with the cast component which can be achieved if the aluminum high pressure casting process is used cannot be even remotely achieved, however.
A positively locking connection which is not developed in an optimum way between the insert part and the cylinder block leads, however, as a rule to merely reduced thermal coupling of the insert part to the cast component, which in turn can result in undesired, thermally induced mechanical stresses in the insert part and/or in the cast component.
Against this background, EP 1 110 644 A1 concerns a method for producing a cylinder crankcase, in which an insert part in the form of a cylinder liner has surfaces which are to be encapsulated by casting and are provided with a silicon oxide layer. According to the method, the insert part is cast into an aluminum alloy.